Studying microwave assisted extraction of Laurus nobilis essential oil: Static and dynamic modeling

Microwave assisted extraction (MAE) is recognized as an efficient technique to obtain essential oils (EO) when compared with conventional processes; its efficacy, however, strongly depends on several processing variables. The aim of this work was to evaluate the effect of selected process variables on the extraction of bay (Laurus nobilis) leaves' EO by means of MAE, as well as to describe and simulate the extraction process by means of static and dynamic models. The effect of each process variable was evaluated through statistical analysis based on a response surface design, varying solvent to feed ratio (s:l, 1:1-1:4 g/ml), microwave power (P, 360-540 W), and stirring speed (s, 0-400 rpm). Optimal conditions for EO extraction were achieved when higher values of P (540 W) and s (400 rpm) were combined with the lowest value of s:l (1:1 g/ml). Selected polynomial dependency for modeling the static results, adequately explained the observed responses. From the dynamic analysis, the agreement of the second order equation with the experimental results confirms that the developed dynamic model describes the transient behavior of MAE of bay leaves' EO. Studied variables and their interactions significantly affected (p < 0.05) not only energy requirement and EO yield, but also the extraction mechanism and model parameters.